Thanks Atom, that's the one Now I remember another mystery movie:

4. A British movie or tv-episode from 1990's. VW Beetle is being chased on a narrow country road. The VW is going at at full speed. Someone is chasing it with another car. Driver of the VW turns to a side road which leads to an dead-end. The chaser follows and stops the VW. He then knocks the driver unconscious and proceeds to push the car down a cliff with the driver inside the car. Just when he is pushing the car downhill his leg gets caught up in a seatbelt on the floor. At this point the car is already moving downhill and he is unable to get his leg away from the car. The unconscious 'driver' then wakes up and at the last moment jumps off the car before it falls down a cliff. The bad guy falls down with the car (a dummy is seen strapped on to the car ).